net/sunrpc/socklib.c

Source file repositories/reference/linux-study-clean/net/sunrpc/socklib.c

File Facts

System
Linux kernel
Corpus path
net/sunrpc/socklib.c
Extension
.c
Size
6805 bytes
Lines
279
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: implementation source
Status
source implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

Dependency Surface

Detected Declarations

Annotated Snippet

struct xdr_skb_reader {
	struct sk_buff	*skb;
	unsigned int	offset;
	bool		need_checksum;
	size_t		count;
	__wsum		csum;
};

/**
 * xdr_skb_read_bits - copy some data bits from skb to internal buffer
 * @desc: sk_buff copy helper
 * @to: copy destination
 * @len: number of bytes to copy
 *
 * Possibly called several times to iterate over an sk_buff and copy data out of
 * it.
 */
static size_t
xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
{
	len = min(len, desc->count);

	if (desc->need_checksum) {
		__wsum csum;

		csum = skb_copy_and_csum_bits(desc->skb, desc->offset, to, len);
		desc->csum = csum_block_add(desc->csum, csum, desc->offset);
	} else {
		if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
			return 0;
	}

	desc->count -= len;
	desc->offset += len;
	return len;
}

static ssize_t
xdr_partial_copy_from_skb(struct xdr_buf *xdr, struct xdr_skb_reader *desc)
{
	struct page **ppage = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
	unsigned int poff = xdr->page_base & ~PAGE_MASK;
	unsigned int pglen = xdr->page_len;
	ssize_t copied = 0;
	size_t ret;

	if (xdr->head[0].iov_len == 0)
		return 0;

	ret = xdr_skb_read_bits(desc, xdr->head[0].iov_base,
				xdr->head[0].iov_len);
	if (ret != xdr->head[0].iov_len || !desc->count)
		return ret;
	copied += ret;

	while (pglen) {
		unsigned int len = min(PAGE_SIZE - poff, pglen);
		char *kaddr;

		/* ACL likes to be lazy in allocating pages - ACLs
		 * are small by default but can get huge. */
		if ((xdr->flags & XDRBUF_SPARSE_PAGES) && *ppage == NULL) {
			*ppage = alloc_page(GFP_NOWAIT);
			if (unlikely(*ppage == NULL)) {
				if (copied == 0)
					return -ENOMEM;
				return copied;
			}
		}

		kaddr = kmap_atomic(*ppage);
		ret = xdr_skb_read_bits(desc, kaddr + poff, len);
		flush_dcache_page(*ppage);
		kunmap_atomic(kaddr);

		copied += ret;
		if (ret != len || !desc->count)
			return copied;
		ppage++;
		pglen -= len;
		poff = 0;
	}

	if (xdr->tail[0].iov_len) {
		copied += xdr_skb_read_bits(desc, xdr->tail[0].iov_base,
					xdr->tail[0].iov_len);
	}

	return copied;
}

Annotation

Implementation Notes